The primary purpose of a color film factory in the tin film transistor-liquid crystal display (TFT-LCD) is to coat photoresist of different colors on a glass substrate and prepare patterns of different colors through exposure, development, post-baking and other processes. The purpose of the developing process of the color film factory is to remove unexposed photoresist on the substrate, retain the exposed photoresist pattern, rinse the glass substrate after exposure with a solution of diluted potassium hydroxide (KO) and then rinse the glass substrate with pure water to remove KO residual liquid. A liquid knife apparatus is added in a connection region between a developing section and a cleaning section of a developing device to rapidly clear the KO residual liquid and development residue on a surface of the substrate, thereby reducing the blocking of a filter in the cleaning section. However, water curtain bifurcation may occur in the uninterrupted production of the liquid knife for a long period of time, and the main reason is because the development residue or other foreign matter falls into a knife edge of the liquid knife and blocks a flow direction. The bifurcated liquid curtain generated due to the residual foreign matter in the liquid knife causes poor development, generating the poor development (Mura) and other undesirable qualities.
To solve the above-mentioned problem, an approach in the related art includes manually cleaning liquid curtain after the equipment is shut down. Specifically, the primarily actions include stuffing a sheet inside a knife edge of a liquid knife in a developing machine, cleaning the interior of the knife edge of the liquid knife automatically back and forth several times in a certain speed, regularly cleaning the residual foreign matter inside the liquid knife in a certain frequency, and the production line is resumed after the cleaning is confirmed to be OK. However, the utilization of the equipment is affected and there is a risk of poor products.